Light emitting element mounting base member, and light emitting device using the light emitting element mounting base member

ABSTRACT

A light emitting element mounting base member for mounting a light emitting element is provided that includes electrical conductor cores, light-reflecting insulating members, and light blocking resin. The insulating members each cover a lateral surface of each of the electrical conductor cores. The insulating members have a reflectivity of 70% or more to light emission wavelength of the light emitting element in a range of 440 nm to 630 nm. The light blocking resin joins at least two insulating members, and is capable of blocking light from the light emitting element by reflecting or absorbing the light. At least one upper surface of the electrical conductor cores, at least one lower surface of the electrical conductor cores are exposed from the insulating members and the light blocking resin respectively.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.15/475,162, filed on Mar. 31, 2017, and claims priority to JapanesePatent Application No. 2016-074,774, filed on Apr. 1, 2016 and JapanesePatent Application No. 2017-061,241, filed on Mar. 27, 2017, thecontents of which are hereby incorporated by reference in theirentirety.

BACKGROUND 1. Field of the Invention

The present disclosure relates to a method of manufacturing a lightemitting element mounting base member, a method of manufacturing a lightemitting device using the light emitting element mounting base member, alight emitting element mounting base member, and a light emitting deviceusing the light emitting element mounting base member.

2. Discussion of the Background

As light sources of various kinds, a light emitting device thatincorporates a light emitting element such as a light emitting diode(LED) chip is used. One of these light emitting devices includes a lightemitting element and a base member on which the light emitting elementis mounted. For example, Japanese Unexamined Patent Publication No.2008-235469 and Japanese Unexamined Patent Publication No. 2010-135718describe light emitting devices using light emitting elements mounted inan assembly of light emitting device housings in which a lead frameobtained by processing a metal sheet by punching, etching or othermethods is integrated with a resin using an insert molding technique.

A process of forming the lead frames in manufacturing an assembly oflight emitting device housings necessitates punching or etching, whichgenerates a large amount of wastes and waste liquid, thereby leading anincrease in costs of the lead frames, and consequently in costs of theultimately manufactured light emitting device.

The present aspects have been made in view of the above-mentionedcircumstances, and an object thereof is to provide a method ofmanufacturing a light emitting element mounting base member with areduced cost, a method of manufacturing a light emitting device usingthe light emitting element mounting base member, a light emittingelement mounting base member, and a light emitting device using thelight emitting element mounting base member.

SUMMARY

A method of manufacturing a light emitting element mounting base memberaccording to one aspect of the present disclosure includes: arranging aplurality of core members each including an electrical conductor coreand a light-reflecting insulating member provided on a surface of theelectrical conductor core; integrally holding the core members with alight blocking resin; and partially removing the insulating members suchthat at least one surface of each of the electrical conductor cores isexposed from the light blocking resin.

Further, a light emitting element mounting base member according to oneaspect of the present disclosure includes: a plurality of electricalconductor cores; a plurality of light-reflecting insulating members thateach cover a lateral surface of each of the electrical conductor cores;and a light blocking resin that joins the at least two insulatingmembers, wherein at least one upper surface of the electrical conductorcores, at least one lower surface of the electrical conductor cores, andthe at least one insulating member disposed around the upper surfacesand the lower surfaces of each of the electrical conductor cores areexposed from the light blocking resin.

A cost reduction can be achieved according to the method, the lightemitting element and the mounting base member.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1A is a schematic cross-sectional view showing a core member;

FIG. 1B is a schematic cross-sectional view showing an insulating spacermember;

FIG. 2 is a schematic diagram illustrating a manufacturing methodaccording to a first embodiment of the present disclosure;

FIG. 3 is a schematic diagram illustrating the manufacturing methodaccording to the first embodiment of the present disclosure;

FIG. 4 is a schematic diagram illustrating the manufacturing methodaccording to the first embodiment of the present disclosure;

FIG. 5 is a schematic diagram illustrating the manufacturing methodaccording to the first embodiment of the present disclosure;

FIG. 6 is a schematic diagram illustrating a light emitting deviceaccording to the first embodiment of the present disclosure;

FIG. 7 is a schematic diagram illustrating a manufacturing methodaccording to a second embodiment of the present disclosure;

FIG. 8 is a schematic diagram illustrating a light emitting deviceaccording to the second embodiment of the present disclosure;

FIG. 9 is a schematic diagram illustrating a manufacturing methodaccording to a third embodiment of the present disclosure;

FIG. 10 is a schematic diagram illustrating the manufacturing methodaccording to the third embodiment of the present disclosure;

FIG. 11 is a schematic diagram illustrating the manufacturing methodaccording to the third embodiment of the present disclosure;

FIG. 12 is a schematic diagram illustrating a bottom view of the firstembodiment of the present disclosure shown in FIG. 4; and

FIG. 13 is a schematic diagram illustrating a cross-sectional view takenalong an A-A line of FIG. 12.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings as necessary. It is to be noted that alight emitting element mounting base member and a method ofmanufacturing a light emitting element mounting base member as describedbelow is intended to implement the technical concept of the presentdisclosure, and the present disclosure is not limited to the followingunless otherwise specified. Further, the description provided in oneembodiment or example is applicable to other embodiment or example. Inthe description of the structure of other embodiment, identical orsimilar members are denoted by identical names, and their detaileddescriptions are omitted as appropriate. The sizes, positional relationsand so on of members shown in the drawings may be exaggerated forclarification of explanations.

First Embodiment

A method of manufacturing a light emitting element mounting base member100 according to a first embodiment includes: arranging a plurality ofcore members 16 each including an electrical conductor core 12 and alight-reflecting insulating member 14 provided on the surface of theelectrical conductor core 12; and integrally holding the core members 16with a light blocking resin 20. Hereinafter, a description will be givenof the method of manufacturing the light emitting element mounting basemember according to the present embodiment with reference to FIGS. 1A to6, 12 and 13.

Arranging Core Members 16

As shown in FIG. 2, the spherical core members 16 are arranged. Here,spherical insulating spacer members 18 each having substantially thesame size as the core member 16 are used to adjust the positions of thecore members 16. Specifically, a row in which one insulating spacermember 18 is disposed between core member sets each formed by aplurality of (four in FIG. 2) core members 16 arranged in line, and arow in which just a plurality of insulating spacer members 18 aredisposed, are alternately repetitively disposed. The core members 16 andthe core member sets are used as electrodes of light emitting devices200. Therefore, the core members 16 or the core member sets areprovided, for example, by several tens to several thousands in numberdepending on the number of the light emitting devices 200 that areproduced using the light emitting element mounting base member 100. Thecore members may be arranged in a one-dimensional array, atwo-dimensional array, or a three-dimensional array in which the coremembers are layered.

As shown in FIG. 1A, the core member 16 has the light-reflectinginsulating member 14 on the entire surface of the spherical electricalconductor core 12. The electrical conductor core 12 may have a shapeother than a sphere, and preferably has a shape that allows aninsulating member to be easily formed on the surface. The size of theelectrical conductor core 12 can be selected as appropriate depending onthe size of a light emitting element 24 to be mounted, and the size ofthe light emitting device 200 obtained in the present embodiment. Forexample, when the electrical conductor core 12 is spherical shape, itmay have a diameter in a range of about 0.1 mm to about 2.0 mm.

The light-reflecting insulating member 14 is formed on the entiresurface of the electrical conductor core 12 by, for example, repeatingthe following step a required number of times: spray-coating the entiresurface of the electrical conductor core 12 with the light-reflectinginsulating member 14 and baking the light-reflecting second insulatingmember 14. The thickness of the light-reflecting insulating member 14may be, for example, about 0.01 to 0.1 mm.

As shown in FIG. 1B, the insulating spacer member 18 is preferablyentirely made of an insulating material. Further, the size and shape ofthe insulating spacer member 18 are preferably substantially identicalto those of the employed core member.

Joining Core Members 16

The core members 16 and the insulating spacer members 18 arranged asshown in FIG. 2 are joined at portions in contact to one another with anadhesive agent or the like. Thus, a core member assembly in which thecore members are joined to each other or the core members and theinsulating spacer member 18 are joined to each other is formed. The coremembers 16 and the insulating spacer members 18 can be held in a lightblocking resin forming operation which will be described later, andtherefore this joining can be omitted in the case where a tentativelyfixing jig is used.

Forming Light Blocking Resin

Subsequently, a light blocking resin composition is injected into themold to form a light blocking resin with a mold that has a substantiallyrectangular parallelepiped-shaped cavity so as to cover the core memberassembly. Thus, as shown in FIG. 3, a substantially rectangularparallelepiped-shape of a base member preparatory body 120 is obtainedin which the core member assembly is completely enclosed in the lightblocking resin 20. A runner and a gate of the mold should be provided asappropriate. Thus, the plurality of core members 16 and the insulatingspacer members 18 are integrally held with the light blocking resin 20.At this time, because the light blocking resin composition can be fedinto a space among the core members 16 and the insulating spacer members18, thereby allowing the light blocking resin 20 to be easily molded. Byvirtue of the core members 16 and the insulating spacer members 18 beingspherical, the shape of the space between them is complicated. Thisimproves adhesion between the core members 16 or the insulating spacermembers 18 and the light blocking resin 20.

Exposing Electrical Conductor Cores

Subsequently, the obtained base member preparatory body 120 has athickness reduced to a predetermined degree by grinding or polishingperformed at its upper and lower surfaces. Thereafter, the at least oneelectrical conductor core 12 are partially exposed from each of theinsulating members 14 and the light blocking resin 20 at an uppersurface and a lower surface of the base member preparatory body. Thus,the electrical conductor cores 12, the insulating members 14 and thelight blocking resin 20 are disposed substantially flush with oneanother at the upper and lower surfaces of the base member preparatorybody.

This provides, as shown in FIGS. 4, 12, and 13, the light emittingelement mounting base member 100 that includes: a plurality ofelectrical conductor cores 12; the light-reflecting insulating members14 that each cover the lateral surface of each of the electricalconductor cores 12; and the light blocking resin 20 that joins the atleast two insulating members 14, and in which the electrical conductorcores 12 are exposed outside the upper and lower surfaces of the lightblocking resin 20. The light blocking resin 20 and the insulatingmembers 14 are removed until the electrical conductor cores 12 arepartially exposed, therefore, the core members 16 may not be completelyenclosed in the light blocking resin 20 in molding the light blockingresin 20 of the base member preparatory body 120. For example, the topof the core member 16 may be exposed from the light blocking resin 20.

Forming Metal Films

Metal films 22 may be formed at the exposed portions of the electricalconductor cores 12 of the light emitting element mounting base member100 by plating or sputtering. In the present embodiment, as shown inFIG. 5, each of the metal films 22 is formed on the exposed surfaces ofthe electrical conductor cores 12, the exposed surfaces of theinsulating members 14, and the surface of the light blocking resin 20 toconnect the exposed surfaces of a plurality of electrical conductorcores 12. Specifically, two metal films 22 are disposed with respect toeach core member set formed by the plurality of core members 16, fourcore members 16 in the present embodiment, arranged in line. That is,one metal film 22 is formed for two core members. The metal films 22 aredisposed to be spaced apart from one another. Because the metal films 22are connected to the light emitting elements 24 or to the outside of thelight emitting device via a connection terminal (e.g., connectors) orthe like, the metal films 22 are preferably made of a material that ishighly electrically conductive and/or capable of establishing goodmechanical and electrical connection. A material having highlight-reflecting property, for example, silver is used for the metalfilm 22 on the upper surface side, in other words, a surface on whichthe light emitting elements 24 are to be mounted. The metal films maynot be formed on all the exposed surfaces of the electrical conductorcores, and need only be formed on necessary areas.

Mounting Light Emitting Element

A plurality of light emitting elements are mounted on the upper surfaceof a metal film-equipped light emitting element mounting base memberobtained as described above. In the present embodiment, the lightemitting elements 24 each including a pair of positive and negativeelectrodes on one surface thereof are flip-chip-mounted on the uppersurface of the light emitting element mounting base member 100 while thesurfaces of the light emitting elements 24 including the electrodes aresituated on the light emitting element mounting base member 100 side. Atthis time, one metal film 22 and the positive or negative electrode ofone of the light emitting elements 24 are electrically connected to eachother. The electrical connection between the light emitting elementmounting base member 100 and the light emitting elements 24 may beperformed using solder, anisotropic conductive paste or the like.

Encapsulating Light Emitting Elements

As shown in FIG. 5, the light emitting elements 24 and the upper surface31 of the light emitting element mounting base member 100 (where thelight emitting elements are mounted) are encapsulated by being coveredwith an encapsulating member 26 to form a light emitting device assembly130.

In the present embodiment, an enlarged area of the light emittingelement mounting base member can increase the number of light emittingelements that are collectively undergone processes such as mounting andencapsulating the light emitting elements. Accordingly, manufacturingcosts can be reduced.

Singulating

The light emitting device assembly 130 is cut and/or divided alongpredetermined cutting/dividing lines and thus singulated, so that eachresultant piece includes at least two core members. Thus, the lightemitting devices 200 shown in FIG. 6 are obtained. The cutting/dividinglines are preferably provided at positions where the electricalconductor cores 12 are not to be cut. For example, the cutting/dividinglines are preferably provided at the positions where a plurality ofinsulating spacer members 18 are cut along the rows where only the lightblocking resin 20 and/or a plurality of insulating spacer members 18 aredisposed. When a proportion of the metal members is high with respect toother members on the cutting/dividing lines for dividing and singulatingthe light emitting device assembly 130, cost of singulation isincreased. For example, in the case where the light emitting deviceassembly 130 is punched with a mold or cut with a dicing blade, thecutting tool wears out faster with metals than with resin. Further,breaking is difficult with a metal member. In the present embodiment,the electrical conductor cores 12 previously separated are integrallyheld to use as the light emitting element mounting base member 100, sothat singulation can be performed without cutting the metal material.Accordingly, cutting can be performed at a high speed, and wear of thecutting blade is reduced, so that productivity can be improved.

By using the previously separated spherical electrical conductor cores12, the resulting light emitting element mounting base member 100 can beeasily produced with a great area.

Further, the light emitting device 100 preferably has a structure thatthe electrical conductor cores 12 immediately below the light emittingelements 24 are each covered with the light-reflecting insulatingmembers 14 with the metal films 22 being formed thereon, because theheat dissipation path (i.e., the electrical conductor cores 12positioned directly below the light emitting elements 24) and thecurrent flow path (i.e., the electrical conductor cores 12 electricallyconnected to the metal films 22 outside the light emitting elements 24)are easily designed to be separated from each other.

Second Embodiment

After the light emitting element mounting base member 100 is produced ina similar manner to the first embodiment, a reflector that is capable ofreflecting light emitted by the light emitting element 24 may be formedon or above the upper surface 31 of the light emitting element mountingbase member 100. For example, as shown in FIG. 7, a reflector 42 isformed using a mold to expose the metal films 22 of the metalfilm-equipped light emitting element mounting base member at the bottomsurface of recesses 40. Alternatively, the reflector 42 may be obtainedby providing a plate-like member that has a plurality of through holes,and joining the plate-like member to the upper surface 31. The metalfilms 22 may be formed after the reflector 42 is formed.

Thereafter, in a similar manner to the first embodiment, the lightemitting elements 24 are mounted and the encapsulating member 26 isembedded in the recess 40. Thus, a light emitting device assembly 130Ais formed.

The light emitting device assembly 130A is cut along predeterminedcutting lines and thus singulated, to obtain light emitting devices 200Aas shown in FIG. 8. In the example shown in FIG. 8, cutting is performedso that each light emitting device 200A has one recess 40. Cutting maybe performed so that each light emitting device 200A has two or morerecesses.

Third Embodiment

A light emitting element mounting base member according to the presentembodiment further includes at least one protection device 50 that iselectrically connected to at least one electrical conductor core 12A andembedded in a light blocking resin 20A.

Arranging Core Members 16A

In the present embodiment, as shown in FIG. 9, cuboid core members 16Aare linearly arranged, to form a bar-like one-dimensional array metalcore assembly 140. The cuboid core members 16A can be formed, forexample, by aligning the spherical core members, and thereafter bringingthem into contact with one another by pressurizing from threedirections, namely, the top-bottom direction, the front-rear direction,and the right-left direction. Each core member 16A has an electricalconductor core 12A, and a light-reflecting insulating member 14A thatcovers the surface of the electrical conductor core 12A. In a regionwhere the core member 16A is electrically connected to the protectiondevice 50, the electrical conductor core 12A is exposed from theinsulating member 14A. For example, the electrical conductor core 12A isexposed by removing the insulating member 14A at one lateral surface ofthe one-dimensional array metal core assembly 140. Instead of removingthe insulating member 14A, the electrical conductor cores 12A and theprotection devices 50 may be electrically connected one another bypiercing bumps provided on the protection devices 50 and breaking theinsulating member 14A.

Mounting Protection Device

As shown in FIG. 9, the protection devices 50 are flip-chip mounted atpredetermined positions where the electrical conductor cores 12A areexposed. Here, the protection devices 50 are mounted so that oneprotection device 50 is positioned across the joining surfaces of theadjacent core members 16A, and the protection device 50 is joined to theelectrical conductor cores 12 with two electrodes of the protectiondevice 50. The electrical connection between the protection device 50and the electrical conductor cores 12 may be performed with solder,anisotropic conductive paste, bumps or the like.

Arranging Insulating Spacer Member 18A

As shown in FIG. 10, the one-dimensional array metal core assemblies 140and the insulating spacer members 18A are alternately aligned andjoined. Thus, a planar array metal core assembly 150 is formed. At thistime, the protection devices 50 are positioned between the lateralsurface of the one-dimensional array metal core assembly 140 and thelateral surface of the insulating spacer member 18A. That is, thejoining is performed so that the protection devices 50 are aligned onthe lateral surface, but not on the upper surface or the lower surface.Recesses for housing the protection devices 50 may be formed on thelateral surface of each insulating spacer member 18A.

Forming Light Blocking Resin

Subsequently, By using a mold that has a substantially rectangularparallelepiped-shaped cavity to cover the planar array metal coreassembly 150, a light blocking resin composition is injected into themold to form the light blocking resin. Thus, a base member preparatorybody is formed that encloses the planar array metal core assembly 150 inthe light blocking resin 20A. At this time, the space between the coremembers 16A and the insulating spacer members 18A where no protectiondevice 50 is present serves as the flow path of the resin composition,and also forms the anchor.

Thereafter, the base member preparatory body has a thickness reduced toa predetermined degree by grinding or polishing performed at its upperand lower surfaces. Thus, the light blocking resin 20A and theinsulating members 14A are partially removed, to expose the electricalconductor cores 12A at the upper and lower surfaces. Consequently, asshown in FIG. 11, the light emitting element mounting base member 100Ais obtained. The following operations are similar to those in the firstand second embodiments.

According to the present embodiment, the protection devices 50 areenclosed in the light emitting element mounting base member 100A, andtherefore light emitted by the light emitting elements are not beabsorbed by the protection devices 50, thereby preventing a reduction inlight emission efficiency of the light emitting devices.

Hereinafter, a description will be given of materials and the likesuitable for the constituent members of the light emitting deviceaccording to the embodiments.

Core Member

The core member at least includes the electrical conductor core and thelight-reflecting insulating member. The core member is, for example, ametal core equipped with a light-reflecting insulating film, a metalsphere equipped with a light-reflecting insulating film or a graphitesphere equipped with a light-reflecting insulating film. The surface ofthe core member may have a fine irregular shape in order to enhancejoining strength with the light blocking resin.

Electrical Conductor Core

The electrical conductor core is a member used as the electrode and/orthe heat dissipation path of the light emitting device. For thispurpose, the electrical conductor core may be made of an electricallyconductive material such as metal. For example, the material of theelectrical conductor core may be metal such as Cu, Al, Ag, Au, Pt, Pd,or Rh or alloy thereof, or a carbon material such as graphite. Theelectrical conductor core preferably reflects light emitted by the lightemitting element mounted on the light emitting element mounting basemember, for example, by 70%, and preferably by 80% or more. For example,in the case where the light emitting element emits blue or bluish light,the electrical conductor core is preferably made of Al, Ag or the like.

The electrical conductor core may be entirely in a single composition,or may have a plurality of regions differing in composition. Forexample, the electrical conductor core may have a multilayer structurein which two or more types of materials are included to form a firstmetal part covered with a second metal part by plating or the like. Theelectrical conductor core may contain an insulating material or membersuch as voids. The electrical conductor core may be made of ananisotropic conductive material, such as a stranded wire or a litz wire.

The shape of the electrical conductor core may be, for example, acylindrical column, a prism (or a polyhedron), a sphere (including anellipsoid), a round pipe (or a round tube), or any three-dimensionalshape similar to the foregoing. The shape of the electrical conductorcore is selected as appropriate depending on the structures provided inthe light emitting element mounting base member, such as a through holeor a castellation.

The electrical conductor core is partially exposed outside the surfaces(i.e., the upper surface 31 and the lower surface 32) of the lightemitting element mounting base member. At the exposed portion, theelectrical conductor core is electrically connected to the lightemitting element using a joining member such as a wire or solder.Accordingly, the electrical conductor core preferably has the size orthe shape which allows the exposed portion to have the area and shapesuitable for establishing connection with the light emitting element.For example, the electrical conductor core is exposed to besubstantially flush with the upper surface and the lower surface of thelight emitting element mounting base member. In the case where the metalfilm described later is provided in such a manner as to cover theexposed portion of the electrical conductor core, the metal film and thelight emitting element are connected to each other via a joining member.

The light emitting element that is mounted on the light emitting elementmounting base member may be in contact with any of the electricalconductor core, the light-reflecting insulating member, and the lightblocking resin. The light emitting element being mounted on theelectrical conductor core facilitates dissipation of heat generated bythe light emitting element. The electrical conductor core and theelectrode of the light emitting element can be directly connected toeach other via an electrically conductive joining member such as solderwithout using wires, thereby achieving a reduction in size of the lightemitting device.

One light emitting element mounting base member is provided with aplurality of core members in order for the electrical conductor cores toserve as the electrodes of the light emitting device. At least twoelectrical conductor cores should be provided to the base member of thelight emitting device to serve as the electrodes of the light emittingdevice. Further, a plurality of electrical conductor cores may be usedas one electrode of the light emitting device. For example, theelectrode of the light emitting element may be joined with theelectrical conductor cores disposed adjacent to each other via anelectrically conductive joining member. The disposition of theelectrically conductive portion in the light emitting element mountingbase member can be changed as appropriate by changing the positioning ofthe core members each having the electrical conductor core. Thisimproves flexibility in designing the light emitting element mountingbase member.

The electrical conductor cores are exposed at the upper surface 31 andthe lower surface 32 of the light emitting element mounting base member.A single electrical conductor core may be exposed at the two positions,namely, at the upper surface and the lower surface. Alternatively, someof the electrical conductor cores may be exposed at the upper surfaceand some others may be exposed at the lower surface. Use of theelectrical conductor core joined to the light emitting element as theexternal terminal of the base member improves the heat dissipationproperty.

In the case where the electrical conductor core is used not as theelectrode but as the heat dissipation path, the electrical conductorcore and the light emitting element may not be electrically connected toeach other, and the electrical conductor core is not necessarily exposedat the surface of the light emitting element mounting base member. Theelectrical conductor core(s) is/are preferably disposed continuouslyfrom around the light emitting element being the heat source to aroundthe outer surfaces of the light emitting element mounting base member,so that heat from the light emitting element is easily released to theoutside.

Light-Reflecting Insulating Member

In the present embodiment, the light-reflecting insulating member coversthe lateral surface of the electrical conductor core. Thelight-reflecting insulating member may have a single-layer structure, ora multilayer structure in which a plurality of layers are stacked. Inthe case of a plurality of layers, a thermosetting resin film can beprovided on the side near the electrical conductor core and a joininglayer on the outermost perimeter. This can achieve good productivity,because none or little adhesive agent is necessary, in forming theassembly of the core members.

The light-reflecting insulating member is formed, for example on thelateral surface of the electrical conductor core, as a single layer filmor a multilayer film in a substantially uniform thickness. Thelight-reflecting insulating member has a thickness, for example, betweenseveral micrometers and several hundred micrometers. Thelight-reflecting insulating member preferably has a thickness of aboutseveral ten micrometers, because both the electrical insulation and areduction in size of the light emitting device (or the light emittingelement mounting base member) can be achieved. The light-reflectinginsulating member may be formed in a substantially uniform thickness onthe lateral surface of the electrical conductor core. Alternatively, thelight-reflecting insulating member may be formed to be thicker at onearea than at other area.

A portion of the electrical conductor core exposed outside the uppersurface and the lower surface of the light emitting element mountingbase member is also exposed from the light-reflecting insulating member.The light-reflecting insulating member is positioned around theelectrical conductor core on the upper surface and the lower surface ofthe base member. The light-reflecting insulating member being interposedbetween a plurality of electrical conductor cores allows the pluralityof electrical conductor cores to be disposed as being insulated fromeach other.

The light-reflecting insulating member is preferably made of a materialusing a resin as a base material in view of costs and manufacturability.A resin such as a thermosetting resin or a thermoplastic resin can beemployed as the resin for the base material. Specific examples of such aresin include an epoxy resin composition; a silicone resin composition;a modified epoxy resin composition such as a silicone modified epoxyresin; a modified silicone resin composition such as an epoxy modifiedsilicone resin; polyimide resin compositions and modified polyimideresin compositions; polyphthalamides (PPA); polycarbonate resins; liquidcrystal polymers (LCP); acrylonitrile butadiene styrene (ABS) resins;phenol resins; acrylic resins; polybutylene terephthalate (PBT) resins;polypropylene resins (PP); polyamides (PA 6 and PA66); polyphenylenesulfide resins (PPS); and polyether ether ketone resins (PEEK). Thematerial of the base material can be selected from materials other thanresin, for example, glass.

In order to provide the base material with light reflectivity, alight-reflecting material in shape of, for example, particulate orfibrous. Specific examples of such materials include titanium dioxide,silicon dioxide, zirconium dioxide, potassium titanate, alumina,aluminum nitride, boron nitride, mullite, niobium oxide, or variouskinds of rare-earth oxides (e.g., yttrium oxide, gadolinium oxide) maybe added to the base material or other member. The light-reflectinginsulating member preferably exhibits high reflectivity to lightemission wavelength of the light emitting element mounted thereon. Forexample, the light-reflecting insulating member is preferably set toexhibit the reflectivity on the average of 70% or more to the lightemitted by the light emitting element in a range of 440 nm to 630 nm.Further, the light-reflecting insulating member preferably exhibits highaverage reflectivity than the employed electrical conductor core, in therange of 440 nm to 630 nm.

The light-reflecting insulating member may be formed in such a manner asto partially expose the electrical conductor core in advance.Alternatively, the entire surface of the electrical conductor core maybe covered with the light-reflecting insulating member, and thereafterthe light-reflecting insulating member may be partially removed, so thatthe surface of the electrical conductor core is exposed from theinsulating member. In the case where the light-reflecting insulatingmember is removed later, for example, thermosetting resin can be usedfor the base material of the light-reflecting insulating member, andthermoplastic resin can be used for the light blocking resin. Therefore,the light-reflecting insulating member can be selectively dissolved witha chemical agent using the difference in dissolving speed. In thismanner, removal of the light-reflecting insulating member can beperformed not only by cutting, but also by dissolving.

Light Blocking Resin

The light blocking resin is an insulating member that integrally holdsthe plurality of core members. Light blocking means herein that theresin is capable of blocking light from the light emitting element(e.g., mainly visible light) by, for example, 70%, preferably 90%, andfurther preferably 95% or more. The light-blocking effect may beattained by reflecting light or absorbing light. The light blockingresin can be white or black, for example. This makes the resin basematerial less likely to degrade due to light.

The light blocking resin may be thermosetting resin, thermoplastic resinor the like. In order to provide such resin with the light blockingproperty against light emitted by the light emitting element mountedthereon, a light-reflecting material, a light absorbing material orother materials can be added. Such an additive may be particulate,fibrous or other shape. The light blocking resin may be formed by asingle material or a plurality of different materials. Further, thelight blocking resin may present not only the space between a pluralityof core members, but may also project on an upper side or a lower side.

Light emitted to the resin positioned vicinity of the light emittingelement (in particular, at the position in contact with the lightemitting element or the position facing the light emitting element) isextremely high in density. As the light emitting device drives, thelight may cause degradation or discoloration of the resin, therebyreducing the light emission efficiency of the light emitting device.Providing light blocking property to the resin positioned immediatelybelow the light emitting element discourages deterioration of the resindue to light, and maintains the light emission efficiency of the lightemitting device.

A resin such as a thermosetting resin or a thermoplastic resin can beemployed as the resin for a base material of the light-blocking resin.Specific examples of such a resin include an epoxy resin composition; asilicone resin composition; a modified epoxy resin composition such as asilicone modified epoxy resin; a modified silicone resin compositionsuch as an epoxy modified silicone resin; a polyimide resin composition,a modified polyimide resin composition; polyphthalamide (PPA); apolycarbonate resin; liquid crystal polymer (LCP); ABS resin; phenolicresin; acrylic resin; PBT resin; polypropylene resin (PP); polyamide(PA6, PA66); polyphenylene sulfide resin (PPS); and polyether etherketone resin (PEEK).

A light-reflecting material is preferably added to such resin. To serveas the light-reflecting material, powder of a reflecting member that isless likely to absorb light from the light emitting element and islargely different in refractive index from the resin serving as the basematerial (e.g., TiO₂, Al₂O₃, ZrO₂, or MgO) may be dispersed. Thus, lightcan be efficiently reflected.

Reflector

The reflector may include the material similar to that of the lightblocking resin described above. Similarly to the light blocking resin,the material preferably contains a light-reflecting material. Thereflector may include a dielectric multilayer film, or a multilayer filmmade up of an insulating film and a metal film.

Metal Film

On the surface of the electrical conductor core exposed at the uppersurface and the lower surface of the light emitting element mountingbase member, the metal film may be formed by plating or the like. Themetal film on the upper surface of the light emitting element mountingbase member, which is a side where the light emitting element ismounted, is preferably made of metal being highly reflective to lightemitted by the light emitting element. The metal film on the lowersurface of the light emitting element mounting base member serving asthe external electrode of the light emitting device is preferably madeof metal that is good in wettability to solder. In consideration ofadhesion between the outermost metal film and the electrical conductorcore, the metal film may include a metal film serving as a base layer.That is, the metal film may have a multilayer structure.

The metal film may be formed not only on the surface of the electricalconductor core, but also on the surface of the light-reflectinginsulating member and/or the light blocking resin. For example, on atleast one electrical conductor core on which the light emitting elementis mounted, the metal film is formed across the surface of theelectrical conductor core exposed at the surface of the light emittingelement mounting base member and the surface of the insulating memberand that of the light blocking resin positioned outside the electricalconductor core. Provision of such a metal film allows heat from thelight emitting element to spread in the lateral direction of the basepart of the light emitting device.

The metal film may function as a wiring layer that electrically connectstwo or more electrical conductor cores to each other. For example, so asto connect between adjacent electrical conductor cores, respectivesurfaces of the electrical conductor cores and the insulating membersand the light blocking resin positioned between the adjacent electricalconductor cores are covered with the metal film. Thus, a serial orparallel wiring can be formed, and flexibility in designing the basemember of the light emitting device improves. For example, when aplurality of light emitting elements are connected in series with theincreased drive voltage and the reduced drive current, the voltage dropor power loss is less likely to occur, thereby improving the energyefficiency as the light source improves.

The metal film may be provided after the formation of the light blockingresin. Alternatively, the metal film may be provided to the electricalconductor core before the formation of the light blocking resin.

Light Emitting Element

Examples of the light emitting element that can be mounted on the lightemitting element mounting base member include a light emitting diode, alaser diode, a light emitting transistor, and a light emittingthyristor.

The light emitting element is preferably mounted on the exposed surfaceof the electrical conductor core in view of heat dissipation. Aninsulating member having good thermal conductivity or a thin insulatingfilm may be provided between the light emitting element and theelectrical conductor core. For example, the light emitting element usingan insulating substrate such as a sapphire substrate can be junction-upmounted on the exposed surface of the electrical conductor core.

In the case where the flip-chip mounting (also referred to as thejunction-down mounting) is performed, at least the pair of electrodes ofthe light emitting element is preferably electrically connected to twoor more electrical conductor cores. In the case where bending stress isapplied to the base part of the light emitting device, the bendingstress tends to concentrate not on the metal portion but on the resinportion that easily deforms than the metal portion. Accordingly, inperforming the flip-chip mounting, bending stress concentrating on theinsulating part present near the light emitting element may break thelight emitting element, disconnect or crack the conductive connectingmember such as solder or bumps, thereby possibly leading non-lighting ofthe light emitting element. By arranging a plurality of electricalconductor cores near the light emitting element, the light emittingelement mounting part of the base part of the light emitting device andthe surrounding part are formed by a plurality of light-reflectinginsulating members or the light blocking resin. Therefore such resinparts disperse the bending stress, and the bending stress is less likelyto concentrate on the region around the light emitting element. As aresult, the present embodiment can reduce light emitting devicefailures, such as non-lighting, due to external stress applied to thebase part.

Further, as compared to a frame-insert type light emitting elementmounting base member, the interval between the adjacent light emittingdevice housings is narrow. Accordingly, in an assembly of the lightemitting device housings, the interval between the light emittingelement mounting parts can be narrowed. Thus, the processing capacity ofthe chip mounter can be increased, to reduce the assembling costs.

Insulating Spacer Member

The light emitting element mounting base member according to the presentembodiment may further include the insulating spacer member. Bydisposing the spacer member between the core member and the core member,the distance between the core members can be set. This enhancesflexibility in designing the light emitting element mounting base memberor the light emitting device.

The insulating spacer member may be made of the material similar to thatof the light-reflecting insulating member. Using a resin material,grinding, cutting, (i.e., singulating) and the like can be easilyperformed. Further, the shape can be determined as appropriate dependingon the design of the light emitting element mounting base member to beobtained. For example, the shape may be a cylindrical column, a prism (apolyhedron), a sphere (including an ellipsoid), a round pipe (a roundtube), or any shape similar to the foregoing. Further, a joining layermay be provided to the outermost perimeter. In order to enhance thejoining force to the light blocking resin, the insulating spacer membermay have fine irregular surfaces.

Other than being spherical, the insulating spacer member may be linearin shape depending on the distance desired to be adjusted, such assquare bar-like or round bar-like shape. Further, the insulating spacermember may be film-like, or sheet-like with a certain thickness.

Protection Device

The light emitting device may include the protection device thatprotects the light emitting element from breakdown due to overcurrent.The protection device may be, for example, a Zener diode or a capacitor.The protection device with an electrode on one side is preferable, sothat the protection device can be face-down mounted without thenecessity of using wires. For example, the protection device isconnected to one of the lateral surfaces of the electrical conductorcore, and provided inside the light emitting element mounting basemember while being covered with the light blocking resin. The insulatingmember is removed from the connecting part between the protection deviceand the electrical conductor core. Thus, the protection device can bedisposed inside the light emitting element mounting base member. Thiscan reduce the risk of light from the light emitting element beingabsorbed or blocked by the protection device, thereby enhancing thelight extraction efficiency of the light emitting device.

Encapsulating Member

The light emitting device may include the encapsulating member forprotecting the light emitting element from external physical andchemical degradation factors. The encapsulating member need only beformed to directly or indirectly cover the light emitting element, andmay be made of silicone resin or epoxy resin as a suitable material, forexample. In case of an UV-LED, optical glass may be employed.

Other Members

The light emitting device may contain a light scattering member and/or awavelength conversion member that converts part of light emitted by thelight emitting element to light of different wavelength. For example,the encapsulating member may contain a wavelength conversion substancesuch as a fluorescent material. A resin member such as the lightblocking resin may contain filler made of any appropriate substance, toadjust the property such as thermal conductivity or thermal expansioncoefficient.

Example 1

As shown in FIG. 1A, a plurality of spherical electrical conductor cores12 made of Cu and each having a diameter of 0.9 mm are provided.Subsequently, on the entire surface of each of the electrical conductorcores 12, the light-reflecting insulating member 14 is formed, which issilicone resin containing titanium oxide, with a thickness of 0.06 mm.Thus, the core members 16 each having a diameter of 1.02 mm areobtained.

Subsequently, as shown in FIG. 2, the core members 16 and the insulatingspacer members 18, which are each a spherical body made of insulatingresin and having a diameter of 1 mm, are arranged. Specifically, in thepresent embodiment, a row in which one insulating spacer member 18 isdisposed between core member sets each formed by a plurality of, four inFIG. 2, core members 16 arranged in line, and a row in which only agroup of insulating spacer members 18 are disposed, are alternativelyrepetitively disposed. The core members 16 or the core member sets areused as the lead electrodes of the light emitting devices 200. Then,they are joined to one another to form a core member assembly.

Subsequently, as shown in FIG. 3, using a mold, a light-reflectingmolded resin composition made of epoxy resin is molded that containstitanium oxide to cover the core member assembly. This provides the basemember preparatory body 120 in which the core member assembly iscompletely enclosed in the light-reflecting molded resin serving as thelight blocking resin 20.

Subsequently, as shown in FIGS. 4, 12, and 13, the obtained base memberpreparatory body 120 has its thickness reduced to a predetermined degreeby grinding or polishing performed at its upper and lower surfaces.Thus, the electrical conductor cores 12 are partially exposed at theupper surface and the lower surface of the base member preparatory body.

Further, as shown in FIG. 5, the metal films 22 are formed on theexposed portions of the electrical conductor cores 12 by plating.

As shown in FIG. 5, a plurality of light emitting elements 24 is mountedon the upper surface of the metal film-equipped light emitting elementmounting base member obtained in this manner. In the present embodiment,the light emitting elements 24 each having the pair of positive andnegative electrodes at one surface are flip-chip mounted, so that thesurface provided with the electrodes faces the metal film-equipped lightemitting element mounting base member. The light emitting elements 24 inthe present embodiment each have dimensions of 0.85 mm in longitudinal,0.65 mm in lateral, and 0.15 mm in thickness. At this time, one metalfilm and the positive or negative electrode of one light emittingelement 24 are connected to each other. The connection between the metalfilm-equipped light emitting element mounting base member and the lightemitting element 24 may be performed with solder, anisotropic conductivepaste or the like.

Subsequently, as shown in FIG. 5, the light emitting elements 24 and theupper surface of the metal film-equipped light emitting element mountingbase member (where the light emitting elements are mounted) are coveredand thus encapsulated with a light-transmissive resin serving as theencapsulating member 26, to form the light emitting device assembly 130.

Then, as shown in FIG. 6, the light emitting device assembly 130 is cutwith a dicing blade along predetermined cutting lines extending alongthe rows where only a group of insulating spacer members 18 is disposed,so that the plurality of insulating spacer members 18 and thelight-reflecting molded resin serving as the light blocking resin 20 arecut. Thus, the light emitting device assembly 130 is singulated toprovide the light emitting devices 200.

Example 2

In order to form the core members, a white-color light-reflectinginsulating member is formed with a thickness of 0.06 mm on each ofspherical electrical conductor cores made of Cu and having a diameter of0.9 mm. Thus, the core members each having a diameter of 1.02 mm isobtained. As shown in FIG. 9, the core members are linearly aligned, andbrought into contact with one another by being pressurized from threedirections, to form the bar-like one-dimensional array metal coreassembly 140. By being pressurized, each of the electrical conductorcores in state of copper spheres becomes cuboid in shape.

The insulating members 14A is removed on one lateral surface of theone-dimensional array metal core assembly 140. On the predeterminedpositions where the insulating members 14A have been removed, Zenerdiodes serving as the protection devices 50 are flip-chip mounted.

Subsequently, as shown in FIG. 10, the one-dimensional array metal coreassemblies 140 and the insulating spacer members 18A are alternatelyaligned and joined. Thus, the planar array metal core assembly 150 isformed. The insulating spacer members 18A are each 0.67 mm square, andhave a length substantially the same as that of the one-dimensionalarray metal core assemblies 140.

In the insert molding technique, the planar array metal core assembly150 is clamped and pressed with a mold to form the light blocking resin20A using a light-reflecting thermoplastic resin composition. Thus, thebase member preparatory body that encloses the planar array metal coreassembly 150 is obtained. The base member preparatory body has athickness reduced to a predetermined degree by grinding or polishingperformed at its upper and lower surfaces. Thus, the metal core surfacesare exposed at the upper and lower surfaces, and the light emittingelement mounting base member 100A as shown in FIG. 11 is formed.

On the exposed respective upper and lower surfaces of the electricalconductor cores 12A, electroplating is performed to form metal films 22,therefore, the metal film-equipped light emitting element mounting basemember is formed. Plating on the upper surfaces on which the lightemitting elements are mounted is performed with light-reflectingmaterial, such as Ag.

On one surface of the metal film-equipped light emitting elementmounting base member, light emitting elements each having the pair ofpositive and negative electrodes positioned at one surface are eachface-down mounted on a predetermined pair of plated electrical conductorcores 12A. Each of the light emitting elements has dimensions of 0.85 mmin longitudinal, 0.65 mm in lateral, and 0.15 mm in thickness.

The interval between the pair of positive and negative electrodes is0.14 mm. The upper surface of the metal film-equipped light emittingelement mounting base member on which the light emitting elements 24 aremounted is covered and thus encapsulated with the encapsulating member26 made of a light-transmissive resin. Thus, the light emitting deviceassembly 130A is formed. Finally, the light emitting device assembly130A is cut with a mold along predetermined cutting lines and thussingulated, to provide the light emitting devices 200.

The present disclosure is applicable to various kinds of light sources,as a base member of a light emitting device that includes at least onelight emitting element such as an LED chip.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A light emitting element mounting base member formounting a light emitting element having an n-side electrode and ap-side electrode on a same side of the light emitting element, the lightemitting element mounting base member comprising: a plurality ofelectrical conductor cores having upper surfaces and lower surfaces, theplurality of electrical conductor cores including a first electricalconductor core and a second electrical conductor core; a plurality oflight-reflecting insulating members, each of which covers a surfaceexcept for the upper surface and the lower surface of each of theplurality of electrical conductor cores, the plurality oflight-reflecting insulating members having a reflectivity of 70% or morewith respect to light emission wavelength of the light emitting elementin a range of 440 nm to 630 nm; a light blocking resin that joins atleast two insulating members of the plurality of light-reflectinginsulating members, the light blocking resin which is capable ofblocking light from the light emitting element by reflecting orabsorbing the light; a first metal film provided on the upper surface ofthe first electrical conductor core; and a second metal film provided onthe upper surface of the second electrical conductor core, wherein theupper surfaces and the lower surfaces of the first electrical conductorcore and the second electrical conductor core are exposed from theplurality of light-reflecting insulating members and the light blockingresin, respectively.
 2. The light emitting element mounting base memberaccording to claim 1, further comprising an insulating spacer memberprovided between the plurality of electrical conductor cores.
 3. Thelight emitting element mounting base member according to claim 1,wherein at least two electrical conductor cores of the plurality ofelectrical conductor cores are electrically connected by the first metalfilm.
 4. The light emitting element mounting base member according toclaim 1, wherein a material of the plurality of electrical conductorcores includes Cu, Al, Ag, Au, Pt, Pd, or Rh, or an alloy thereof. 5.The light emitting element mounting base member according to claim 1,wherein a material of the plurality of electrical conductor coresincludes graphite.
 6. The light emitting element mounting base memberaccording to claim 1, wherein each of the plurality of electricalconductor cores is a partial sphere having at least one flat surface atthe upper surface or the lower surface thereof.
 7. The light emittingelement mounting base member according to claim 6, wherein each of theplurality of electrical conductor cores has a diameter in a range of 0.1mm to 2.0 mm.
 8. The light emitting element mounting base memberaccording to claim 1, wherein at least one light-reflecting insulatingmember of the plurality of light-reflecting insulating members has athickness of 0.01 to 0.1 mm.
 9. The light emitting element mounting basemember according to claim 1, wherein the light blocking resin is capableof blocking 70% or more of the light from the light emitting element.10. A light emitting device for mounting a light emitting element havingan n-side electrode and a p-side electrode on a same side of the lightemitting element, the light emitting device comprising: the lightemitting element mounting base member according to claim 1; and thelight emitting element that is mounted on the light emitting elementmounting base member and electrically connected to the plurality ofelectrical conductor cores.
 11. The light emitting device according toclaim 10, wherein the n-side electrode and the p-side electrode are onthe same side of the light emitting element adjacent to the lightemitting element mounting base member, and the plurality of electricalconductor cores and the n-side electrode and the p-side electrode arerespectively electrically connected to each other.
 12. The lightemitting device according to claim 10, further comprising a protectiondevice that is electrically connected to the plurality of electricalconductor cores and covered with the light blocking resin.